Kasey Kahne rests on the the roof of his car during the race introductions NASCAR Sprint Cup Sharpie 500 at Bristol Motor Speedway in Bristol Tennessee, August 23, 2008. [Photo/Agencies]

Celebrities may resist the urge to send a stream of consciousness on Twitter in the new year, after famous people tweeted their way into trouble on everything from boxer briefs to breast-feeding in 2011.

NASCAR driver Kasey Kahne became the latest celebrity to blunder on Twitter, when he recently had to apologize for a tweet critical of public breast-feeding.

But Kahne has been far from alone in discovering Twitter's pitfalls. The year 2011 saw Congressman Anthony Weiner resign in a scandal that began with an errant tweet, and the musings of Hollywood stars such as the tech savvy Ashton Kutcher and comic Gilbert Gottfried generated public controversy.

As a result of those and other scandals, 2011 may be seen as a turning point when more celebrities and politicians saw the dangers of Twitter and quit sending unfiltered messages, pop culture experts said.

The public already knows speeches and even snappy quips from public figures are often scripted, so fans are likely to understand if the handlers of celebrities play a larger role in managing their Twitter accounts.

"There was a time from 2008 to 2011 where Twitter was like, whatever was on your mind you tweeted about it -- literally mindlessly," said radio host Cooper Lawrence, author of "The Cult of Celebrity."

"Now you're going to see the other side of the bell curve, where people are more cautious. Politicians are already more cautious," she said.

In Washington, D.C., no better example of a Twitter train wreck can be found than the career of former Rep. Anthony Weiner, a once influential Democrat from New York.

The spark that led to revelations about Weiner and his resignation in June was a tweet he sent to a female college student, with a lewd photo of his bulging boxer underwear.

"That guy has become now the patron saint of warning people that communicating from the id, which is exactly what Twitter is designed to do, can end up being a really, really bad idea," said Bob Thompson, professor of television and pop culture at Syracuse University.

DUCKING OUT

Comedian Gilbert Gottfried did not have his career ruined by Twitter, but it cost him a lucrative gig.

Gottfried fired off several joke tweets in March about the devastating earthquake and tsunami in Japan. In one message, he said: "Japan is really advanced. They don't go to the beach. The beach comes to them."

Gottfried was roundly criticized in the media, and insurance company Aflac Inc fired him as the voice of its iconic duck in television commercials.

"Being the Aflac voice was a large portion of his income, and not being able to do that for years and years to come is going to cost him millions of dollars," said Jo Piazza, author of the book "Celebrity, Inc.: How Famous People Make Money."

More than other celebrities, actor Ashton Kutcher has been a master of Twitter. Kutcher became the first to have a million followers on the site. He also created the online production company Katalyst and embarked on lucrative promotion campaigns for such products as Popchips.

All of that made it believable when Kutcher in September was given a starring role as a billionaire technology guru on hit television comedy "Two and a Half Men."

Kutcher took over from actor Charlie Sheen, who clashed with the show's co-creator and raised eyebrows on Twitter with descriptions of himself as "winning."

In November, Kutcher created a public uproar when he tweeted a defense of Penn State football coach Joe Paterno, who was fired in the fallout from a sexual abuse scandal that centered on assistant coach Jerry Sandusky.

Kutcher apologized in a blog post, and said he did not know about the abuse scandal when he sent the off-the-cuff tweet that read, "How do you fire Jo Pa?" He also pledged to have his staff at Katalyst manage his Twitter account, as opposed to posting on his own as he had done before.

The 33-year-old actor wrote that Twitter has turned into a "mass publishing platform" in which tweets can quickly "become news that is broadcast around the world and misinformation becomes volatile fodder for critics."

Experts say Kutcher's Twitter mistake and his decision to alter the way he uses the site could serve as a lesson to others. "Because after all, he is a master of the form," Thompson said.

The recent controversy surrounding Kasey Kahne shows that not only a celebrity's tweet, but also the response to other online commentators can generate trouble.

He originally posted a comment about encountering a mother breast-feeding at a supermarket. "Took second look because I was obviously seeing things. I wasn't!" he wrote.

But Kahne faced just as much heat for a crude comment directed at a woman online who criticized his view on public breast-feeding. The racer later apologized for both messages.

Other notable Twitter controversies of 2011 include film critic Roger Ebert's tweet, "Friends don't let jackasses drink and drive," which was sent in response to the impaired driving death of "Jackass" star Ryan Dunn.

In a less inflammatory Twitter misfire, Charlie Sheen in December revealed his phone number, in an apparent attempt to send it privately to teen singer Justin Bieber.